The present invention relates to an analysis machine for analyzing the cleanness condition of relatively transparent strips that are used especially in the area of photography; and more specifically a device which permits a non-destructive analysis of the cleanness condition of the surfaces of perforated strips, in order to check whether the cleanness condition of these strips is satisfactory in view of the later use of the strips.
There are many methods of detection and measurement of elements or particles that pollute or contaminate by adhesion surfaces or flat strips by adhesion, especially the surfaces of filmstrips or photographic papers.
U.S. Pat. No. 4,189,235 relates to a device that enables the dynamic measurement of the accumulation of dust in certain zones of a barely transparent banknote. The banknote to be tested is positioned between an optical system comprising a light source and a receiving optical system comprising a microscope and photodiodes. The light emitted towards the receiving cell depends on the amount of dust accumulated on the inspected zone. The light is transformed into an electrical signal by a transducer and the electrical signal is analyzed, to determine the number and quantity of dust accumulated in the inspected zone of the banknote.
U.S. Pat. No. 4,669,885 discloses a process and a system of optical inspection that enable the direct, rapid and comparison-free detection of unwanted particles that adhere in particular to semiconductor or printed circuit plates. The principle is based on an optical device comprising sources of light, laser rays, or x-rays and projection and detection means enabling an image of the inspected printed circuit to be obtained; thus enabling the identification, according to the indices of reflection and transmission, of the following elements: the plate having unwanted matter, the positioning of each particle of unwanted matter on the plate, and especially on the lines making up the printed circuit. The usefulness of this method and the associated means is to measure accurately the faults rapidly and directly on the production line for semiconductor plates.
U.S. Pat. No. 5,033,095 discloses a process and a device to automatically determine and quantify the value of the particles the pollute sheets used in the paper industry. The strip of material to be inspected is passed manually or automatically into a scanner type image analyzer, in order to produce an image that is then computer analyzed line by line to enable, via an analog-digital conversion module, the comparative line by line measurement of each pixel of the image, and then the detection of whether the continuity between two successive lines is normal or not, which is based on defining a recognized and preset acceptance threshold or level for the particles appearing on the analyzed image. Data concerning the particles that pollute the paper sheets is stored in a memory, which can be classified by preset categories, and a paper report concerning these particles can be produced.
U.S. Pat. No. 5,402,228 discloses a process and a device that enable the measurement and recording of the size and intensity of small dust type marks or faults appearing on a paper strip. The method uses a dust counter that comprises in particular a device enabling the holding of the paper strip to be inspected, an optical system and CCD (charge couple device) sensors linked to an electronic computer. An analysis process, starting with the recording of analog image data in a database, and using digital image conversion, enables the comparison of the digital image of the inspected paper strip with preset references of values of marks or dust stored in the computer""s memory. A histogram linked to the condemning dust marks is constructed from the database and reference thresholds, thus enabling the analysis of the pollution rates of the inspected paper strips.
U.S. Pat. No. 5,436,979 discloses an improvement of the processes previously in existence, especially described in U.S. Pat. No. 4,189,235 and U.S. Pat. No. 5,033,095, in the sense that it enables the measurement, by quantification and characterization, of anomalies such as dust and scratches remaining on the surface of a sample of photographic film, after the sample of photographic film has undergone a cleaning procedure; in order to verify the efficiency of the cleaning procedure. U.S. Pat. No. 5,436,979 describes a reliable and robust automatic process that using a scanner and a computer enables noise or variations of luminous intensity or lighting occurring in time to be allowed for when measuring, especially between two consecutive measurements; by reconditioning the original image, so that variations of luminosity not coming from the anomalies to be measured are eliminated from the reconstituted image to be analyzed that then only contains the anomalies. This method, improved by comparison with the previous state of the art, is based on a digital electronic processing process of the scanned image that enables noise or lighting variations to be eliminated.
The processes and devices described in the above mentioned patents that use as a base a means of lighting the sample of the strip to be inspected, come up against a significant problem when perforated strips are inspected, in the sense that the light source transmits luminous rays into the perforations, which constitutes a major disturbing element for the measurement of the anomalies, especially near these perforations, and going well beyond the simples light variations referred to in U.S. Pat. No. 5,436,979. In the case of dust measurements to be carried out on perforated strips, it is preferable to practically completely get rid of significant disturbance or noise due to the emitted light rays that cross the perforations made in the strips to be analyzed and that strongly disturb the measurements, and to do this without even having to use, for instance, digital-analog conversion means of the perforated filmstrip analyzed.
The present invention overcomes the above-noted problem by enabling a fast, efficient and accurate measurement to be made, without image conversion or processing, of the pollution by particle of the surface of perforated strips, by using a specific device for supporting and guiding the strip to be analyzed. The device enables the practically complete masking of the perforations made in the strip when it passes through the automatic analysis machine, and thus enables the detection and analysis of the anomalies due to the unwanted particles deposited abnormally on the whole surface of the analyzed strips.
The present invention relates to an automatic machine for analyzing a surface cleanness condition of relatively transparent strips. The machine comprises a structure and electromechanical components adapted to hold and convey at least one strip to be analyzed; a light source adapted to light the at least one strip; a recording device adapted to detect, record and view the surface of the at least one strip; and a supporting and guiding device for supporting and guiding the at least one strip while in a lighting and recording zone. The supporting and guiding device enabling a substantial masking of perforations made in the at least one strip, when it runs in the automatic machine.